Disclaimer¶
This program comes with no warranty.You must use this program at your own risk.
Introduction¶
aria2 is a utility for downloading files. The supported protocols areHTTP(S), FTP, SFTP, BitTorrent, and Metalink. aria2 can download afile from multiple sources/protocols and tries to utilize your maximumdownload bandwidth. It supports downloading a file fromHTTP(S)/FTP/SFTP and BitTorrent at the same time, while the datadownloaded from HTTP(S)/FTP/SFTP is uploaded to the BitTorrentswarm. Using Metalink's chunk checksums, aria2 automatically validateschunks of data while downloading a file like BitTorrent.
The project page is located at https://aria2.github.io/.
See the aria2 Online Manual (Russian translation, Portuguesetranslation) to learnhow to use aria2.
Features¶
Here is a list of features:
Command-line interface
Download files through HTTP(S)/FTP/SFTP/BitTorrent
Segmented downloading
Metalink version 4 (RFC 5854) support(HTTP/FTP/SFTP/BitTorrent)
Metalink version 3.0 support(HTTP/FTP/SFTP/BitTorrent)
Metalink/HTTP (RFC 6249) support
HTTP/1.1 implementation
HTTP Proxy support
HTTP BASIC authentication support
HTTP Proxy authentication support
Well-known environment variables for proxy:
http_proxy
,https_proxy
,ftp_proxy
,all_proxy
andno_proxy
HTTP gzip, deflate content encoding support
Verify peer using given trusted CA certificate in HTTPS
Client certificate authentication in HTTPS
Chunked transfer encoding support
Load Cookies from the file using the Firefox3 format, Chromium/Google Chromeand the Mozilla/Firefox(1.x/2.x)/Netscape format.
Save Cookies in the Mozilla/Firefox (1.x/2.x)/Netscape format.
Custom HTTP Header support
Persistent Connections support
FTP/SFTP through HTTP Proxy
Download/Upload speed throttling
BitTorrent extensions: Fast extension, DHT, PEX, MSE/PSE,Multi-Tracker, UDP tracker
BitTorrent WEB-Seeding.aria2 requests chunk more than piece size to reduce the requestoverhead. It also supports pipelined requests with piece size.
BitTorrent Local Peer Discovery
Rename/change the directory structure of BitTorrent downloadscompletely
JSON-RPC (over HTTP and WebSocket)/XML-RPC interface
Run as a daemon process
Selective download in multi-file torrent/Metalink
Chunk checksum validation in Metalink
Can disable segmented downloading in Metalink
Netrc support
Configuration file support
Download URIs found in a text file or stdin and the destinationdirectory and output file name can be specified optionally
Parameterized URI support
IPv6 support with Happy Eyeballs
Disk cache to reduce disk activity
Versioning and release schedule¶
We use 3 numbers for the aria2 version: MAJOR.MINOR.PATCH. We will shipMINOR updates on the 15th of every month. We may skip a release if we havehad no changes since the last release. The feature and documentationfreeze happens 10 days before the release day (the 5th day of the month)for translation teams. We will raise an issue about the upcomingrelease around that day.
We may release PATCH releases between regular releases if we havesecurity issues.
The MAJOR version will stay at 1 for the time being.
How to get source code¶
We maintain the source code at Github:https://github.com/aria2/aria2
To get the latest source code, run the following command:
$ git clone https://github.com/aria2/aria2.git
This will create an aria2 directory in your current directory and sourcefiles are stored there.
Dependency¶
features | dependency |
---|---|
HTTPS | OSX or GnuTLS or OpenSSL or Windows |
SFTP | libssh2 |
BitTorrent | None. Optional: libnettle+libgmp or libgcryptor OpenSSL (see note) |
Metalink | libxml2 or Expat. |
Checksum | None. Optional: OSX or libnettle or libgcryptor OpenSSL or Windows (see note) |
gzip, deflate in HTTP | zlib |
Async DNS | C-Ares |
Firefox3/Chromium cookie | libsqlite3 |
XML-RPC | libxml2 or Expat. |
JSON-RPC over WebSocket | libnettle or libgcrypt or OpenSSL |
Note
libxml2 has precedence over Expat if both libraries are installed.If you prefer Expat, run configure with --without-libxml2
.
Note
On Apple OSX, OS-level SSL/TLS support will be preferred. Henceneither GnuTLS nor OpenSSL is required on that platform. If you'dlike to disable this behavior, run configure with--without-appletls
.
GnuTLS has precedence over OpenSSL if both libraries are installed.If you prefer OpenSSL, run configure with --without-gnutls
--with-openssl
.
On Windows, there is SSL implementation available that is based onthe native Windows SSL capabilities (Schannel) and it will bepreferred. Hence neither GnuTLS nor OpenSSL is required on thatplatform. If you'd like to disable this behavior, run configurewith --without-wintls
.
Note
On Apple OSX, the OS-level checksum support will be preferred,unless aria2 is configured with --without-appletls
.
libnettle has precedence over libgcrypt if both libraries areinstalled. If you prefer libgcrypt, run configure with--without-libnettle --with-libgcrypt
. If OpenSSL is selected overGnuTLS, neither libnettle nor libgcrypt will be used.
If none of the optional dependencies are installed, an internalimplementation that only supports md5 and sha1 will be used.
On Windows, there is SSL implementation available that is based onthe native Windows capabilities and it will be preferred, unlessaria2 is configured with --without-wintls
.
A user can have one of the following configurations for SSL and cryptolibraries:
OpenSSL
GnuTLS + libgcrypt
GnuTLS + libnettle
Apple TLS (OSX only)
Windows TLS (Windows only)
You can disable BitTorrent and Metalink support by providing--disable-bittorrent
and --disable-metalink
to the configurescript respectively.
To enable async DNS support, you need c-ares.
c-ares: http://c-ares.haxx.se/
How to build¶
aria2 is primarily written in C++. Initially, it was written based onC++98/C++03 standard features. We are now migrating aria2 to the C++11standard. The current source code requires a C++11 aware compiler. Forwell-known compilers, such as g++ and clang, the -std=c++11
or-std=c++0x
flag must be supported.
To build aria2 from the source package, you need the followingdevelopment packages (package name may vary depending on thedistribution you use):
libgnutls-dev (Required for HTTPS, BitTorrent, Checksum support)
nettle-dev (Required for BitTorrent, Checksum support)
libgmp-dev (Required for BitTorrent)
libssh2-1-dev (Required for SFTP support)
libc-ares-dev (Required for async DNS support)
libxml2-dev (Required for Metalink support)
zlib1g-dev (Required for gzip, deflate decoding support in HTTP)
libsqlite3-dev (Required for Firefox3/Chromium cookie support)
pkg-config (Required to detect installed libraries)
You can use libgcrypt-dev instead of nettle-dev and libgmp-dev:
libgpg-error-dev (Required for BitTorrent, Checksum support)
libgcrypt-dev (Required for BitTorrent, Checksum support)
You can use libssl-dev instead oflibgnutls-dev, nettle-dev, libgmp-dev, libgpg-error-dev and libgcrypt-dev:
libssl-dev (Required for HTTPS, BitTorrent, Checksum support)
You can use libexpat1-dev instead of libxml2-dev:
libexpat1-dev (Required for Metalink support)
On Fedora you need the following packages: gcc, gcc-c++, kernel-devel,libgcrypt-devel, libxml2-devel, openssl-devel, gettext-devel, cppunit
If you downloaded source code from a git repository, you have to installthe following packages to get autoconf macros:
libxml2-dev
libcppunit-dev
autoconf
automake
autotools-dev
autopoint
libtool
And run the following command to generate configure script and other filesnecessary to build the program:
$ autoreconf -i
Also, you need Sphinx to build the man page.
If you are building aria2 for Mac OS X, take a look atthe makerelease-osx.mk GNU Make makefile.
The quickest way to build aria2 is first to run configure script:
$ ./configure
To build statically linked aria2, use ARIA2_STATIC=yes
command-line option:
$ ./configure ARIA2_STATIC=yes
After configuration is done, run make
to compile the program:
$ make
See Cross-compiling Windows binary to create a Windows binary.See Cross-compiling Android binary to create an Android binary.
The configure script checks available libraries and enables as manyfeatures as possible except for experimental features not enabled bydefault.
Since 1.1.0, aria2 checks the certificate of HTTPS servers by default.If you build with OpenSSL or the recent version of GnuTLS which hasgnutls_certificate_set_x509_system_trust()
function and thelibrary is properly configured to locate the system-wide CAcertificates store, aria2 will automatically load those certificatesat the startup. If it is not the case, I recommend supplying the pathto the CA bundle file. For example, in Debian the path to CA bundlefile is '/etc/ssl/certs/ca-certificates.crt' (in ca-certificatespackage). This may vary depending on your distribution. You can giveit to configure script using --with-ca-bundle option
:
$ ./configure --with-ca-bundle='/etc/ssl/certs/ca-certificates.crt'$ make
Without --with-ca-bundle
option, you will encounter the error whenaccessing HTTPS servers because the certificate cannot be verifiedwithout the CA bundle. In such a case, you can specify the CA bundle fileusing aria2's --ca-certificate
option. If you don't have the CA bundlefile installed, then the last resort is to disable the certificatevalidation using --check-certificate=false
.
Using the native OSX (AppleTLS) and/or Windows (WinTLS) implementationwill automatically use the system certificate store, so--with-ca-bundle
is not necessary and will be ignored when usingthese implementations.
By default, the bash_completion file named aria2c
is installed tothe directory $prefix/share/doc/aria2/bash_completion
. To changethe install directory of the file, use --with-bashcompletiondir
option.
After a make
, the executable is located at src/aria2c
.
aria2 uses CppUnit for automated unit testing. To run the unit test:
$ make check
Cross-compiling Windows binary¶
In this section, we describe how to build a Windows binary using amingw-w64 (http://mingw-w64.org/doku.php) cross-compiler on DebianLinux. The MinGW (http://www.mingw.org/) may not be able to buildaria2.
The easiest way to build Windows binary is using Dockerfile.mingw. SeeDockerfile.mingw how to build a binary. If you cannot use Dockerfile,then continue to read the following paragraphs.
Basically, after compiling and installing depended libraries, you cando cross-compile just passing appropriate --host
option andspecifying CPPFLAGS
, LDFLAGS
, and PKG_CONFIG_LIBDIR
variables to configure. For convenience and to lower our owndevelopment cost, we provide an easier way to configure the buildsettings.
mingw-config
script is a configure script wrapper for mingw-w64.We use it to create official Windows build. This script assumesthe following libraries have been built for cross-compile:
c-ares
expat
sqlite3
zlib
libssh2
cppunit
Some environment variables can be adjusted to change build settings:
HOST
cross-compile to build programs to run on
HOST
. It defaults toi686-w64-mingw32
. To build a 64bit binary, specifyx86_64-w64-mingw32
.PREFIX
Prefix to the directory where dependent libraries are installed. Itdefaults to
/usr/local/$HOST
.-I$PREFIX/include
will beadded toCPPFLAGS
.-L$PREFIX/lib
will be added toLDFLAGS
.$PREFIX/lib/pkgconfig
will be set toPKG_CONFIG_LIBDIR
.
For example, to build a 64bit binary do this:
$ HOST=x86_64-w64-mingw32 ./mingw-config
If you want libaria2 dll with --enable-libaria2
, then don't useARIA2_STATIC=yes
and prepare the DLL version of externallibraries.
Cross-compiling Android binary¶
In this section, we describe how to build Android binary using AndroidNDK cross-compiler on Debian Linux.
At the time of this writing, Android NDK r21e should compile aria2without errors.
android-config
script is a configure script wrapper for Androidbuild. We use it to create an official Android build. This scriptassumes the following libraries have been built for cross-compile:
c-ares
openssl
expat
zlib
libssh2
When building the above libraries, make sure that disable sharedlibrary and enable only static library. We are going to link thoselibraries statically.
android-config
assumes that $ANDROID_HOME
and $NDK
environment variables are defined.
We currently use Android NDK r21e. $NDK
should point to thedirectory to Android NDK. The build tools will be found under$NDK/toolchains/llvm/prebuilt/linux-x86_64/bin/
.
All the dependent libraries must be installed under$ANDROID_HOME/usr/local
.
After android-config
, run make
to compile sources.
Building documentation¶
Sphinx is used to building thedocumentation. aria2 man pages will be build when you run make
ifthey are not up-to-date. You can also build an HTML version of the aria2man page by make html
. The HTML version manual is also availableonline (Russiantranslation, Portuguesetranslation).
BitTorrent¶
About file names¶
The file name of the downloaded file is determined as follows:
- single-file mode
If "name" key is present in .torrent file, the file name is the valueof "name" key. Otherwise, the file name is the base name of .torrentfile appended by ".file". For example, .torrent file is"test.torrent", then file name is "test.torrent.file". Thedirectory to store the downloaded file can be specified by -doption.
- multi-file mode
The complete directory/file structure mentioned in .torrent fileis created. The directory to store the top directory ofdownloaded files can be specified by -d option.
Before download starts, a complete directory structure is created ifneeded. By default, aria2 opens at most 100 files mentioned in.torrent file, and directly writes to and reads from these files.The number of files to open simultaneously can be controlled by--bt-max-open-files
option.
DHT¶
aria2 supports mainline compatible DHT. By default, the routing tablefor IPv4 DHT is saved to $XDG_CACHE_HOME/aria2/dht.dat
and therouting table for IPv6 DHT is saved to$XDG_CACHE_HOME/aria2/dht6.dat
unless files exist at$HOME/.aria2/dht.dat
or $HOME/.aria2/dht6.dat
. aria2 uses thesame port number to listen on for both IPv4 and IPv6 DHT.
UDP tracker¶
UDP tracker support is enabled when IPv4 DHT is enabled. The portnumber of the UDP tracker is shared with DHT. Use --dht-listen-port
option to change the port number.
Other things should be noted¶
-o
option is used to change the file name of .torrent file itself,not a file name of a file in .torrent file. For this purpose, use--index-out
option instead.The port numbers that aria2 uses by default are 6881-6999 for TCPand UDP.
aria2 doesn't configure port-forwarding automatically. Pleaseconfigure your router or firewall manually.
The maximum number of peers is 55. This limit may be exceeded whenthe download rate is low. This download rate can be adjusted using
--bt-request-peer-speed-limit
option.As of release 0.10.0, aria2 stops sending request messages afterselective download completes.
Metalink¶
The current implementation supports HTTP(S)/FTP/SFTP/BitTorrent. Theother P2P protocols are ignored. Both Metalink4 (RFC 5854) andMetalink version 3.0 documents are supported.
For checksum verification, md5, sha-1, sha-224, sha-256, sha-384, andsha-512 are supported. If multiple hash algorithms are provided, aria2uses a stronger one. If whole file checksum verification fails, aria2doesn't retry the download and just exits with a non-zero return code.
The supported user preferences are version, language, location,protocol, and os.
If chunk checksums are provided in the Metalink file, aria2 automaticallyvalidates chunks of data during download. This behavior can be turnedoff by a command-line option.
If a signature is included in a Metalink file, aria2 saves it as a fileafter the completion of the download. The file name is downloadfile name + ".sig". If the same file already exists, the signature file isnot saved.
In Metalink4, a multi-file torrent could appear in metalink:metaurlelement. Since aria2 cannot download 2 same torrents at the sametime, aria2 groups files in metalink:file element which has the sameBitTorrent metaurl, and downloads them from a single BitTorrent swarm.This is a basically multi-file torrent download with file selection, sothe adjacent files which are not in Metalink document but share the samepiece with the selected file are also created.
If relative URI is specified in metalink:url or metalink:metaurlelement, aria2 uses the URI of Metalink file as base URI to resolvethe relative URI. If relative URI is found in the Metalink file which isread from the local disk, aria2 uses the value of --metalink-base-uri
option as base URI. If this option is not specified, the relative URIwill be ignored.
Metalink/HTTP¶
The current implementation only uses rel=duplicate links. aria2understands Digest header fields and check whether it matches thedigest value from other sources. If it differs, drop the connection.aria2 also uses this digest value to perform checksum verificationafter the download is finished. aria2 recognizes geo value. To tell aria2which location you prefer, you can use --metalink-location
option.
netrc¶
netrc support is enabled by default for HTTP(S)/FTP/SFTP. To disablenetrc support, specify -n command-line option. Your .netrc fileshould have correct permissions(600).
WebSocket¶
The WebSocket server embedded in aria2 implements the specificationdefined in RFC 6455. The supported protocol version is 13.
libaria2¶
The libaria2 is a C++ library that offers aria2 functionality to theclient code. Currently, libaria2 is not built by default. To enablelibaria2, use --enable-libaria2
configure option. By default,only the shared library is built. To build a static library, use--enable-static
configure option as well. See libaria2documentation to know how to use API.
References¶
aria2 Online Manual
https://aria2.github.io/
RFC 6266 Use of the Content-Disposition Header Field in the Hypertext Transfer Protocol (HTTP)
BitTorrent: UDP Tracker Protocol for BitTorrentand BitTorrent udp-tracker protocol specification.
Kademlia: A Peer-to-peer Information System Based on the XOR Metric